JP5635088B2 - Polyolefin artificial leather - Google Patents

Description

(Cross-reference of related applications)
This application claims the benefit of US Provisional Application No. 61 / 226,082, filed Jul. 16, 2009.
The present invention relates to artificial leather. In one aspect, the invention relates to an artificial leather comprising a multilayer structure, while in another aspect, the invention relates to the aforementioned structure comprising a top skin layer, an intermediate foam layer, and a bottom fabric layer.

  Artificial leather made from polyolefin (PO) resin, such as polyethylene (PE), polypropylene (PP), etc. is cheaper than natural leather and polyvinyl chloride (PVC) or cast polyurethane (PU) leather While avoiding most of the disadvantages of artificial leather made from PVC-based or PU-based resins, it has an inherent set of problems. PO-based resins generally need to be blended with an elastic resin to increase the softness of the artificial leather or reduce its hardness in order to match the softness of artificial leather made using flexible PVC resin. . However, not all elastic materials are compatible with all polyolefins, requiring the use of paraffin oil to achieve the desired flexibility in the final product even in situations where compatibility is not an issue. Often done. Furthermore, artificial leather manufactured using a PO-based resin containing elastic material and paraffin oil can exhibit the same hardness and flexibility as those of artificial leather manufactured using flexible PVC. Even so, the unique characteristics of PO-based resins are an obstacle to their use as substitutes for PVC-based resins. These inherent features include a high melting point, rapid cooling during roll processing (due to crystallization), tackiness (as a result of the presence of low molecular weight components), and very poor adhesion to polar materials. .

  In one embodiment, the present invention is an artificial leather including a multilayer structure including a bottom fabric layer and at least one of an uppermost skin layer and a foam layer. In one embodiment, the present invention is an artificial leather including a bottom fabric layer and an uppermost skin layer. In one embodiment, the present invention is an artificial leather comprising a bottom fabric layer and a coated foam layer. The top skin layer is unfoamed and includes a propylene-alpha-olefin copolymer in combination with one or more elastic compounds, and the foam layer also includes propylene-alpha- in combination with one or more elastic compounds. The olefin as well as the fabric layer includes a flexible polymeric material.

  In one embodiment, the present invention is an artificial leather comprising a multilayer structure comprising a top skin layer, an intermediate foam layer and a bottom fabric layer. The top skin layer is unfoamed and includes a propylene-alpha-olefin copolymer in combination with one or more elastic compounds, and the foam layer also includes propylene-alpha- in combination with one or more elastic compounds. The olefin as well as the fabric layer includes a flexible polymeric material.

In one embodiment, the present invention provides:
A. A top skin comprising a propylene / alpha-olefin copolymer and (i) at least one of a styrenic block copolymer, (ii) a homogeneously branched ethylene / alpha-olefin copolymer, (iii) an olefin block copolymer and (iv) a random polypropylene copolymer Layers,
B. An intermediate foam comprising a propylene / alpha-olefin copolymer and (i) at least one of a styrenic block copolymer, (ii) a homogeneously branched ethylene / alpha-olefin copolymer, (iii) an olefin block copolymer and (iv) a random polypropylene copolymer. Layers,
C. A multi-layer structure including a bottom fabric layer comprising a flexible polymeric material.

  In one embodiment, the multilayer structure further includes a primer layer in contact with the top skin layer, such as chlorinated polypropylene (CPP), and a topcoat layer in contact with the primer layer, such as polyurethane (PU).

1 is a first schematic view of a two-layer structure of the present invention. 2 is a second schematic diagram of the two-layer structure of the present invention. 1 is a schematic diagram of a three-layer structure of the present invention. 1 is a schematic diagram of a five-layer structure of the present invention.

(Definition)
For the purposes of U.S. patent practice, the contents of any referenced patents, patent applications or publications, in their entirety, are not limited to synthetic techniques, definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure) and For disclosure of general knowledge in the field, incorporated by reference (or equivalent US version thereof is incorporated by reference as well).

  The numerical ranges in this disclosure are approximate, and may include values outside that range unless otherwise indicated. The numerical range includes all values from the lowest value up to and including the lowest value in increments of 1 unit, but at least 2 units between any lower value and any higher value The condition is that there is a separation.

  “Polymer” means a polymeric compound prepared by polymerizing monomers, whether of the same type or different types. The generic term polymer thus encompasses the term homopolymer commonly used to refer to polymers prepared from only one type of monomer, and the term copolymer as defined below.

  “Copolymer”, “copolymer” and like terms mean a polymer prepared by the polymerization of at least two different types of monomers. These general terms refer to both polymers prepared from two different types of monomers and polymers prepared from more than two different types of monomers, such as terpolymers, tetrapolymers, and the like.

  "Layer" and like terms mean a single thickness or coating of a compound, polymer or composition that has been spread or coated on a surface.

  “Multilayer structure” and similar terms mean a structure comprising two or more layers. The multilayer structure of the present invention includes a top skin layer, an intermediate foam layer, a bottom fabric layer, and optionally a primer layer and a topcoat layer. Each layer includes an upper outer surface and a lower outer surface, and typically and preferably, the lower outer surface of the topcoat layer is in contact with the upper outer surface of the intermediate foam layer, and the lower outer surface of the intermediate foam layer. The surface is in contact with the upper outer surface of the bottom fabric layer. When optional primer and topcoat layer are present, the lower outer surface of the primer layer is in contact with the upper outer surface of the uppermost skin layer, and the upper outer surface of the primer layer is the lower part of the topcoat layer. In contact with the outer surface. “In contact” means that there is no intervening layer, eg, an adhesive layer, between the two outer surfaces.

  The terms “planar surface”, “outer surface”, “upper surface”, “lower surface” and the like are used in distinction from “end surface”. If the shape or outline is rectangular, the layer will include two opposing planar surfaces connected by four end surfaces (two opposing end surfaces, each pair intersecting the other pair at a right angle). Let's go. If the profile is circular, the layer will include two opposing planar surfaces connected by one continuous end surface. Multilayer structures can be of any size and shape, and so can planar and end surfaces, such as thin or thick, polygonal or circular, flat or wavy.

  "Calendaring" and similar terms are used in the context of the present invention to put a molten polymer into a sheet by passing the molten polymer through a series of rollers to coalesce the polymer into a flat and flat sheet or film. Means a mechanical process to convert.

  “Lamination” and like terms mean the process of applying a film, typically a film of plastic or similar material, to a substrate that can be another film. The film can be applied to the substrate with or without an adhesive. In the absence of adhesive, the film and / or substrate can be heated to effect heat or melt lamination. Lamination is a product of the laminating process, and these products are multi-layered. That is, they comprise a film layer in contact with at least two layers, a base layer or a substrate layer.

  “Nonwoven fabric” and like terms mean a fabric or similar material made from long fibers bonded together by chemical, mechanical, thermal or solvent treatment. The term is used to indicate a fabric, such as felt, that is neither woven nor knitted.

  "Spunbond fabric" and like terms mean a fabric or similar material made by depositing extruded spun filaments uniformly and randomly on a collection and collecting belt and then bonding the fibers.

  “Foam” and like terms mean a material formed by trapping multiple bubbles in a liquid or solid.

(Multilayer structure)
FIG. 1A is a schematic diagram of a two-layer structure 10 </ b> A in which the uppermost skin layer 11 is on and in contact with the bottom fabric layer 13. Each layer includes two opposing outer surfaces, an upper outer surface 11a and a lower outer surface 11b of the uppermost skin layer 11, and an upper outer surface 13a and a lower outer surface 13b of the bottom fabric layer 13. The lower outer surface 11b is in contact with the upper outer surface 13a. The upper outer surface 11a and the lower outer surface 13b are open to the environment (i.e., exposed) or, in some cases, are in contact with another surface. The thickness of each layer can vary for convenience and the total thickness of the structure can also vary. Typically, the thickness of the top skin layer is 0.05 to 3, more typically 0.08 to 2, and even more typically 0.1 to 1, millimeters (mm), and the bottom The thickness of the fabric layer is 0.05 to 3, more typically 0.08 to 2.5 and even more typically 0.1 to 2, mm. The total structure thickness is typically 0.1 to 6, more typically 0.15 to 5, and even more typically 0.2 to 3, mm.

  FIG. 1B is a schematic diagram of a two-layer structure 10B in which the foam layer 12 is on and in contact with the bottom fabric layer 13. Each layer includes two opposing outer surfaces, an upper outer surface 12a and a lower outer surface 12b of the foam layer 11, and an upper outer surface 13a and a lower outer surface 13b of the sole fabric layer 13. The lower outer surface 12b is in contact with the upper outer surface 13a. The upper outer surface 12a and the lower outer surface 13b are open to the environment (i.e., exposed) or, in some cases, are in contact with another surface. The thickness of each layer can vary for convenience and the total thickness of the structure can also vary. Typically, the thickness of the foam layer is 0.05 to 3, more typically 0.08 to 2.5 and even more typically 0.1 to 2, millimeters (mm), and The thickness of the bottom fabric layer is 0.05 to 3, more typically 0.08 to 2.5 and even more typically 0.1 to 2, mm. The total structure thickness is typically 0.1 to 6, more typically 0.15 to 5, and even more typically 0.2 to 4, mm.

  FIG. 1C shows that the uppermost skin layer 11 is on the intermediate foam layer 12 and is in contact with the intermediate foam layer 12, and the intermediate foam layer 12 is on the bottom fabric layer 13. 1 is a schematic illustration of a three-layer structure 10C in contact with Each layer has two opposing outer surfaces, an upper outer surface 11a and a lower outer surface 11b of the uppermost skin layer 11, an upper outer surface 12a and a lower outer surface 12b of the intermediate foam layer 12, and an upper outer surface 13a of the bottom fabric layer 13. And a lower outer surface 13b. The lower outer surface 11b is in contact with the upper outer surface 12a, and the lower outer surface 12b is in contact with the upper outer surface 13a. The upper outer surface 11a and the lower outer surface 13b are open to the environment (i.e., exposed) or, in some cases, are in contact with another surface. The thickness of each layer can vary for convenience and the total thickness of the structure can also vary. Typically, the thickness of the top skin layer is 0.05 to 3, more typically 0.08 to 2 and even more typically 0.1 to 1, millimeters (mm) The layer thickness is 0.05 to 3, more typically 0.08 to 2.5 and even more typically 0.1 to 2, mm, and the thickness of the bottom fabric layer is 0.00. 5 to 3, more typically 0.08 to 2.5 and even more typically 0.1 to 2, mm. The total structure thickness is typically 0.15 to 9, more typically 0.24 to 7, and even more typically 0.3 to 5, mm.

  1D shows that the optional primer layer 14 is on and in contact with the top skin layer 11 of the three-layer structure 10C, and the optional topcoat layer 15 is the primer layer 14. 5 is a schematic illustration of a five-layer structure 10D in contact with the primer layer 14. Each optional layer includes two opposing outer surfaces, an upper outer surface 15a and a lower outer surface 15b of the optional topcoat layer 15, and an upper outer surface 14a and a lower outer surface 14b of the optional primer layer 14. . The lower outer surface 15b is in contact with the upper outer surface 14a, and the lower outer surface 14b is in contact with the upper outer surface 11a. In this embodiment, the upper outer surface 15a and the lower outer surface 13b are exposed to the environment or possibly in contact with the outer surface of another structure. The thickness of each optional layer can vary to convenience, and the thickness of the optional topcoat layer is typically 0.1 to 100, more typically 1 to 50 and even more typical. The thickness of the optional primer layer is typically from 0.1 to 100, more typically from 1 to 50 and even more typically from 3 to 10. 10, μm. Again, the thickness of a typical three-layer structure can vary widely, but is typically 0.15 to 9, more typically 0.24 to 7, and even more typically 0.3 to 5. , Mm thickness (the optional topcoat layer and primer layer add little to the total (5 layer) structure thickness). The thickness of the topcoat layer is typically less than the thickness of the uppermost skin layer.

  The two or three layer structure of the present invention can laminate one layer to another layer in any order, i.e., laminate the top skin layer to the bottom fabric layer, or laminate the foam layer to the bottom fabric layer, optionally Then, the uppermost skin layer is laminated on the foam layer, or the uppermost skin layer is laminated on the intermediate foam layer, and then the bottom fabric layer is laminated on the intermediate foam layer, or the uppermost skin layer and the bottom fabric are laminated on the intermediate foam layer. Manufactured by laminating layers simultaneously. If the multilayer structure also includes an optional primer and topcoat layer, it is usually not necessary to apply the epithelium, the intermediate foam and the bottom fabric layer after laminating them together. Typically, the primer layer is roll-coated on the upper outer surface of the uppermost skin layer, and then the topcoat material is coated on the primer layer. Two and three layer structures, ie, structures 10A, 10B, and 10C in FIGS. 1A, 1B, and 1C, respectively, are non-adhesive structures. That is, they do not contain an adhesive layer between any layers, i.e. between the foam layer and the top skin layer and in contact with the foam layer and the top skin layer, or between the foam layer and the bottom fabric layer. And does not contain an adhesive layer that is in contact with the foam layer and the bottom fabric layer, or between the top skin layer and the bottom fabric layer and in contact with the top skin layer and the bottom fabric layer.

  The multilayer structure of the present invention comprises at least two layers: a fabric layer and at least one of a propylene / alpha-olefin-based foam layer and a propylene / alpha-olefin-based top skin layer. In some cases, the multilayer structure may include additional layers applied to the exposed outer surface of the top skin and / or fabric layer. In one embodiment, a primer, such as a halogenated polyolefin, such as chlorinated polypropylene (CPP), is applied to the exposed outer surface of the topmost skin layer, and a topcoat material, such as polyurethane, is applied to the exposed outer surface of the primer layer. Turn on. The purpose of the backing or fabric layer is to withstand the structure, i.e. leather molding, and to be stable against foaming of the intermediate foam layer at high temperatures, e.g. When present, the foam layer provides flexibility to the multilayer structure and also provides cushioning, softness, thermal insulation, light weight and feel. When present, the top skin layer provides protection against UV radiation, heat and other outdoor exposure factors, and it may have visible functionality such as printing, embossing, color and / or gloss. The purpose of the topcoat layer is to protect the uppermost skin layer and the entire structure from scratches, scratches and abrasions, to apply letters and designs to the surface, and to provide an aesthetically pleasing finish. The purpose of the primer layer is to help attach the topcoat layer to the topmost skin layer.

In one embodiment, the multilayer structure of the present invention is characterized by at least one of the following features.
1. A non-halogenated formulation (of the embodiment in which the artificial leather of the present invention contains a halogenated hydrocarbon in the primer layer) that uses a polyolefin-based formulation to mimic physical properties, natural leather feel and relief retention properties. In some cases, the amount of halogen in the artificial leather is so slight that it has a negative, if any, negative effect on the recyclability of the leather compared to the amount of halogen in PVC-based artificial leather. );
2. Elimination of migratory plasticizers;
3. Reduced density and weight compared to PU-based and PVC-based formulations, and exclusion of PU and PVC compounds from the formulation;
4). UV stable and non-yellowing;
5. Fully recyclable using existing scrap recovery and reprocessing technology;
6). 6. Physical and mechanical properties comparable to current artificial leather formulations A propylene / alpha-olefin copolymer based foam layer for good hand feel, eg softness, smoothness etc. and flexibility;
8). 8. Propylene / alpha-olefin copolymer based topcoat layer; Eliminates or reduces hydrolysis due to field exposure compared to PU or TPU leather.
In certain embodiments, the multilayer structure features 2, 3, 4, 5, 6, 7, 8 or all 9 of these features.

(Top skin layer)
The top skin layer (layer 11 in FIGS. 1A, 1C and 1D) comprises a propylene / alpha-olefin copolymer, preferably a propylene / ethylene copolymer, (i) a styrenic block copolymer, (ii) a homogeneously branched ethylene / alpha. -An olefin copolymer, (iii) at least one of an olefin block copolymer and (iv) a random polypropylene copolymer. In one embodiment, the top skin layer comprises a propylene / alpha-olefin copolymer and (i) a styrenic block copolymer, (ii) a homogeneously branched ethylene / alpha-olefin copolymer, (iii) an olefin block copolymer and (iv) ) Including at least two or at least three or all four of the random polypropylene copolymers. The top skin layer may comprise a single propylene / alpha-olefin copolymer or may comprise a blend of two or more propylene / alpha-olefin copolymers. Similarly, each of (i) a styrenic block copolymer, (ii) a homogeneously branched ethylene / alpha-olefin copolymer, (iii) an olefin block copolymer, and (iv) a random polypropylene copolymer may be present neat, Or it may exist as a blend of two or more copolymers. The top skin layer is optionally selected with one or more additives such as processing aids, extenders, blocking agents, pigments and / or dyes, antioxidants, UV stabilizers or absorbers, flame retardants, fillers (E.g., talc, calcium carbonate), and the like.

  The top skin layer typically comprises at least 10, more typically at least 20, and even more typically at least 30, weight percent (wt%) propylene / alpha-olefin copolymer. The maximum amount of propylene / alpha-olefin copolymer in the topcoat layer typically does not exceed 90 wt%, more typically does not exceed 80 wt%, and even more typically 70 wt%. Do not exceed.

  The total amount of (i) styrenic block copolymer, (ii) homogeneously branched ethylene / alpha-olefin copolymer, (iii) olefin block copolymer and (iv) random polypropylene copolymer in the uppermost skin layer is typically at least 10 More typically at least 20 and even more typically at least 30% by weight. The maximum total amount of (i) styrenic block copolymer, (ii) homogeneously branched ethylene / alpha-olefin copolymer, (iii) olefin block copolymer and (iv) random polypropylene copolymer in the uppermost skin layer is typically 90 It does not exceed wt%, more typically does not exceed 80 wt%, and even more typically does not exceed 70 wt%.

  If present, the total amount of optional adhesive present in the topmost skin layer is typically greater than zero phr, more typically at least 1 phr, and even more typically at least 2 phr. (Phr = parts per hundred resin). If present, the total amount of optional adhesive in the uppermost skin layer typically does not exceed 10 phr, more typically does not exceed 7 phr, and even more typically does not exceed 5 phr.

  If present, the total amount of optional filler in the uppermost skin layer is typically greater than zero weight percent (wt%), more typically at least 5 wt%, and even more typically at least 10% by weight. If present, the total amount of optional adhesive in the topmost skin layer typically does not exceed 60%, more typically does not exceed 40%, and even more typically 20%. Does not exceed% by weight.

  The top skin layer is blended or compounded with each other in any conventional mixing device, such as a Banbury kneader or any suitable extruder, under conditions and for a time that produces at least a substantially homogeneous mixture, and Thereafter, the mixture is generally prepared by calendering the mixture using conventional equipment and conditions for forming the sheet. The sheet is then laminated to the intermediate foam layer using conventional laminating equipment and conditions.

(Foam layer)
The foam or intermediate foam layer (layer 12 in FIGS. 1B-1D) is also a propylene / alpha-olefin copolymer, preferably a propylene / ethylene copolymer, (i) a styrenic block copolymer, (ii) a homogeneously branched ethylene / alpha. -An olefin copolymer, (iii) at least one of an olefin block copolymer and (iv) a random polypropylene copolymer. In certain embodiments, the intermediate foam layer comprises a propylene / alpha-olefin copolymer and at least 2, 3, or all four of components (i)-(iv). The intermediate foam layer may comprise a single propylene / alpha-olefin copolymer or may comprise a blend of two or more propylene / alpha-olefin copolymers. Similarly, each of (i) a styrenic block copolymer, (ii) a homogeneously branched ethylene / alpha-olefin copolymer, (iii) an olefin block copolymer, and (iv) a random polypropylene copolymer may be present neat, Or it may exist as a blend of two or more copolymers. The intermediate foam layer will also contain gas from the decomposed blowing agent and any unreacted residual blowing agent. The intermediate foam layer may contain one or more optional additives such as processing aids, extenders, blocking agents, pigments and / or dyes, antioxidants, UV stabilizers and / or absorbers, flame retardants , Fillers (eg, talc, calcium carbonate), and the like.

  The intermediate foam layer typically comprises at least 30, more typically at least 40, and even more typically at least 50, weight percent (wt%) propylene / alpha-olefin copolymer. The maximum amount of propylene / alpha-olefin copolymer in the intermediate foam layer typically does not exceed 90 wt%, more typically does not exceed 80 wt%, and even more typically 70 wt%. Do not exceed. The intermediate foam layer can be compositionally the same as the top skin layer, except for gases and by-products that may result from the foaming process.

  The total amount of (i) styrenic block copolymer, (ii) homogeneously branched ethylene / alpha-olefin copolymer, (iii) olefin block copolymer and (iv) random polypropylene copolymer in the intermediate foam layer is typically at least 10 More typically at least 20 and even more typically at least 30% by weight. The maximum total amount of (i) styrenic block copolymer, (ii) homogeneously branched ethylene / alpha-olefin copolymer, (iii) olefin block copolymer and (iv) random polypropylene copolymer in the intermediate foam layer is typically 70 Does not exceed wt%, more typically does not exceed 60 wt%, and even more typically does not exceed 50 wt%.

  Generally, the blowing agent is introduced into the resin composition to be foamed in an amount ranging from 0.1 to 30, preferably 1 to 20, and more preferably 2 to 10, phr. Typically, sufficient to suppress the activation of the blowing agent into the melt stream, i.e., foaming of the melt stream during the introduction of the blowing agent and subsequent processing of the composition, Introduce under enough pressure to suppress until ready to foam.

  If present, the total amount of optional adhesive present in the foam layer is typically greater than zero phr, more typically at least 1 phr, and even more typically at least 2 phr. If present, the total amount of optional adhesive in the foam layer typically does not exceed 10 phr, more typically does not exceed 7 phr, and even more typically does not exceed 5 phr.

  If present, the total amount of optional filler in the foam layer is typically greater than zero weight percent (wt%), more typically at least 5 wt%, and even more typically at least 10 wt%. % By weight. If present, the total amount of optional filler in the foam layer typically does not exceed 60 wt%, more typically does not exceed 40 wt%, and even more typically 20 wt%. Not exceed.

  The foam layer may be blended or compounded with each other in any conventional mixing device, such as a Banbury kneader or any suitable extruder, under conditions and for a time to produce at least a substantially homogeneous mixture, By calendering the mixture using conventional equipment and conditions for forming, and then heat laminating the sheet to the topcoat layer and / or bottom fabric layer using conventional lamination equipment and conditions In general, prepare. The foam layer is typically foamed until after it is laminated to at least one of the topcoat layer and the bottom fabric layer, and preferably to both layers (in the case of a three or more layer structure). Not subject to conditions. Foaming conditions are such that very fine and regular cells are formed throughout the layer. Typical foaming conditions include an oven temperature of 220 ° C. or higher and an oven residence time of 100 to 120 seconds. Foam efficiency [ie, the ratio of foam volume to original (non-foam) volume] is based on the thickness ratio, typically 50 to 350, more typically 150 to 250. The sheet typically exhibits a tensile strength of 5 to 90 kilograms per square centimeter (kgf / cm 2), an elongation of 100 to 1000%, and a tear strength of 5 to 50 kgf / cm.

(Bottom fabric layer)
The bottom fabric layer comprises a flexible polymeric material that may be woven, non-woven, knitted, flat knitted, spunbonded, etc., which may be natural and / or May contain synthetic fibers. In one embodiment, the fabric layer is a non-woven polymeric spunbond material of 100-500, more typically 150-400 and even more typically 200-350, grams per square meter (g / m ² ). It is. Fabrics that can be used in the practice of the present invention include cotton, silk, and various types based on polyolefins (eg, polyethylene, polypropylene, etc.), nylons, polyesters, polyurethanes (eg, spandex materials) and the like. Examples of synthetic fibers include, but are not limited to. In one embodiment, preferred fabrics are prepared from polyester, polyethylene or polypropylene. The fabric may or may not be subjected to a pre-lamination treatment such as corona surface treatment, impregnation, etc. and finally a foam layer or top skin layer is heat laminated to it.

(Propylene-alpha-olefin copolymer)
The base polymer of the uppermost skin and the intermediate foam layer is a propylene / alpha-olefin copolymer characterized by having a substantially isotactic propylene sequence. A “substantially isotactic propylene sequence” is a sequence greater than 0.85, in alternative embodiments greater than 0.90, in another alternative embodiment 0.92 as determined by ¹³ C NMR. Means having an isotactic triad (mm) that is greater than and in another alternative embodiment greater than 0.93. Isotactic triads are well known in the art and are described, for example, in US Pat. No. 5,504,172 and WO 00/01745, which are copolymers determined by ¹³ C NMR spectra. An isotactic arrangement is mentioned in terms of triad units in the molecular chain.

  The propylene / alpha-olefin copolymer may have a melt flow rate (MFR) in the range of 0.1 to 25 g / 10 minutes, measured according to ASTM D-1238 (at 230 ° C./2.16 kg). All individual values and subranges from 0.1 g / 10 min to 25 g / 10 min are included in this range and are disclosed by this range; for example, MFR is 0.1 g / 10 min, 0.2 g / It can be from a lower limit of 10 minutes or 0.5 g / 10 minutes to an upper limit of 25 g / 10 minutes, 15 g / 10 minutes, 10 g / 10 minutes, 8 g / 10 minutes or 5 g / 10 minutes. For example, a propylene / alpha-olefin copolymer may have an MFR in the range of 0.1 to 10 g / 10 minutes; or a propylene / alpha-olefin copolymer has an MFR in the range of 0.2 to 10 g / 10 minutes. May have.

Propylene / alpha-olefin copolymers include units derived from propylene and one or more alpha-olefin comonomers. Propylene / alpha - Exemplary comonomers utilized to manufacture the olefin copolymer, _{C 10} alpha from _{C 2} and _{C 4} - olefins; for _{example, C 2, C 4, C} 6 and _{C 8} alpha - olefin. The propylene / alpha-olefin copolymer comprises 1 to 30% by weight of one or more units derived from one or more alpha-olefin comonomers.

A propylene / alpha-olefin copolymer is defined as a weight average molecular weight (M _w / M _n ) divided by a number average molecular weight of 3.5 or less or 3.0 or less or 1.8 to 3.0. Having a molecular weight distribution (MWD).

  Such propylene / alpha-olefin copolymers are further described in US Pat. Nos. 6,960,635 and 6,525,157. Such propylene / alpha-olefin copolymers are commercially available from The Dow Chemical Company under the trade name VERSIFY or from ExxonMobil Chemical Company under the trade name VISTAMAXX.

(Styrene block copolymer)
Styrenic block copolymers suitable for the present invention are EP 0 712 892 B1, WO 2004/041538 A1, US Pat. No. 6,582,829 B1, US Patent Application Publication No. 2004/0087235 A1, U.S. Patent Application Publication No. 2004/0122408 A1, U.S. Patent Application Publication No. 2004/0122409 A1, and U.S. Pat. Nos. 4,789,699, 5,093,422 and 5,332,613. It is described in.

  In general, hydrogenated styrenic block copolymers suitable for the present invention are preferably at least two mono-alkenyl arene blocks separated by a saturated conjugated diene block containing less than 20% residual ethylenic unsaturation, preferably a saturated polybutadiene block, preferably Has two polystyrene blocks. Although preferred styrenic block copolymers have a linear structure, in some embodiments, branched or radial polymers or polyfunctionalized block copolymers are useful compounds (amine functionalized styrenic block copolymers are generally described in the present invention). For the production of artificial leather).

  Typically, polystyrene-saturated polybutadiene-polystyrene and polystyrene-saturated polyisoprene-polystyrene block copolymers have polystyrene end blocks having a number average molecular weight of 5,000 to 35,000 and a number average of 20,000 to 170,000. And saturated polybutadiene or saturated polyisoprene having a molecular weight. Saturated polybutadiene blocks preferably have a 35-55% 1,2-configuration, and saturated polyisoprene blocks preferably contain more than 85% 1,4 configurations.

  The total number average molecular weight of the styrenic block copolymer is preferably 30,000 to 250,000 when the copolymer has a linear structure. Such block copolymers typically have an average polystyrene content of 10 wt% to 65 wt%, more typically 10 wt% to 40 wt%.

  SEBS (S is styrene, E is ethylene, and B is butylene) and SEPS (P is propylene) block copolymers useful in certain embodiments of the present invention are Kraton Polymers, Asahi Kasei and Available from Kuraray America.

(Uniformly branched ethylene / alpha-olefin copolymer)
Uniformly branched ethylene / alpha-olefin copolymers useful in the practice of the present invention are produced using single site catalysts such as metallocene catalysts or geometrically constrained catalysts, and typically less than 105C, preferably It has a melting point of less than 90C, more preferably less than 85C, even more preferably less than 80C and even more preferably less than 75C. This melting point is measured by differential scanning calorimetry (DSC) as described, for example, in US Pat. No. 5,783,638. Such ethylene / α-olefin copolymers having a low melting point often exhibit desirable flexibility and thermoplastic properties useful in making the artificial leather of the present invention.

The α-olefin is preferably a C _3-20 linear, branched or cyclic α-olefin. Examples of C _3-20 α-olefins include propene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene and 1-octadecene is mentioned. α-Olefins may also contain cyclic structures such as cyclohexane or cyclopentane, resulting in α-olefins such as 3-cyclohexyl-1-propene (allylcyclohexane) and vinylcyclohexane. For the purposes of the present invention, certain cyclic olefins such as norbornene and related olefins are α-olefins, although some or all of the α-olefins described above are not α-olefins in the classical sense of this term. They can be used instead of. Similarly, styrene and its related olefins (eg, α-methylstyrene, etc.) are α-olefins for the purposes of the present invention. Illustrative uniformly branched ethylene / alpha-olefin copolymers include ethylene / propylene, ethylene / butene, ethylene / 1-hexene, ethylene / 1-octene, ethylene / styrene, and the like. Illustrative terpolymers include ethylene / propylene / 1-octene, ethylene / propylene / butene, ethylene / butene / 1-octene, and ethylene / butene / styrene. The copolymer may be random or blocky.

  More specific examples of homogeneously branched ethylene / alpha-olefin copolymers useful in the present invention include homogeneously branched linear ethylene / alpha-olefin copolymers (eg, TAFMER by Mitsui Petrochemicals Company Limited ( And EXACT® from Exxon Chemical Company), and homogeneously branched, substantially linear ethylene / α-olefin polymers (eg, AFFINITY® available from The Dow Chemical Company) and ENGAGE (registered trademark)). Substantially linear ethylene copolymers are particularly preferred and are described in more detail in US Pat. Nos. 5,272,236, 5,278,272, and 5,986,028. Yes. Blends of any of these copolymers can be used in the practice of the present invention.

(Olefin block copolymer)
Olefin block copolymers that can be used in the practice of the present invention are multiblock or segmented copolymers. These are polymers containing two or more chemically distinct regions or segments (referred to as “blocks”) linked in a linear fashion, i.e. in a polymerized ethylenic functional group rather than in a pendant or grafted manner. A polymer containing chemically different units linked end to end. In certain embodiments, the blocks are the amount or type of comonomer incorporated therein, the density, the amount of crystallization, the crystal size that can be attributed to the polymer of such composition, the type or degree of stereoregularity (isotactic). Tic or syndiotactic), regioregularity or irregularity, the amount of branching (including long chain or hyperbranching), uniformity, or any other chemical or physical property. Multi-block copolymers are characterized by a unique distribution of polydispersity index (PDI or M _w / M _n ), block length distribution, and / or block number distribution due to the unique manufacturing process of these copolymers. More specifically, when produced in a continuous process, polymer embodiments have from about 1.7 to about 8, in other embodiments from about 1.7 to about 3.5, and in other embodiments from about 1. It may have a PDI ranging from 7 to about 2.5, and in still other embodiments from about 1.8 to about 2.5 or from about 1.8 to about 2.1. When produced in a batch or semi-batch process, polymer embodiments have from about 1.0 to about 2.9, in other embodiments from about 1.3 to about 2.5, and in other embodiments from about 1.4. Can have a PDI ranging from about 1.4 to about 1.8, and in still other embodiments.

An ethylene / α-olefin multiblock copolymer is a polymerization characterized by multiple (ie, two or more) blocks or segments of one or more polymerized monomer units that differ in chemical or physical properties. In a modified form (block copolymer), preferably in the form of a multiblock copolymer, comprising ethylene and one or more copolymerizable α-olefin comonomers. In some embodiments, the multiblock copolymer has the following formula:
(AB) _n

Where n is an integer of at least 1, preferably greater than 1, eg 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more; “A” represents a hard block or segment; and “B” represents a soft block or segment. Preferably, A and B are connected linearly rather than branched or star-shaped. A “hard” segment refers to a block of polymerized units in which ethylene is present in an amount greater than 95 weight percent in some embodiments and greater than 98 weight percent in other embodiments. In other words, the monomer content in the hard segment is less than 5 weight percent in some embodiments and 2 weight percent in other embodiments of the total weight of the hard segment. In some embodiments, the hard segment comprises all or substantially all ethylene. On the other hand, a “soft” segment has a comonomer content greater than 10 weight percent, in some embodiments, greater than 5 weight percent, or in various other embodiments, greater than 8 weight percent of the total weight of the soft segment. Refers to a block of polymerized units that is greater or greater than 15 weight percent. In some embodiments, the comonomer content in the soft segment may be greater than 20 weight percent, may be greater than 25 weight percent, may be greater than 30 weight percent, and may be greater than 40 weight percent May be greater than 45 weight percent, may be greater than 50 weight percent, or may be greater than 60 weight percent in various other embodiments.

(Random polypropylene copolymer)
Random propylene polymers generally comprise 90 mole percent or more units derived from propylene. The balance of the units in the propylene copolymer is derived from at least one α-olefin unit.

The α-olefin component of the propylene copolymer is preferably ethylene (considered as an α-olefin for purposes of the present invention) or C _4-20 linear, branched or cyclic α-olefin. Examples of C _4-20 α-olefins include 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene and 1-hexene. Octadecene is mentioned. α-Olefins may also contain cyclic structures such as cyclohexane or cyclopentane, resulting in α-olefins such as 3-cyclohexyl-1-propene (allylcyclohexane) and vinylcyclohexane. For the purposes of the present invention, certain cyclic olefins, such as norbornene and related olefins, especially 5-ethylidene-2-norbornene, are α-olefins and are described above, although in the classical sense of this term are not α-olefins. They can be used in place of some or all of the α-olefins. Similarly, styrene and its related olefins (eg, α-methylstyrene, etc.) are α-olefins for the purposes of the present invention. Illustrative random propylene copolymers include, but are not limited to, propylene / ethylene, propylene / 1-butene, propylene / 1-hexene, propylene / 1-octene, and the like. Illustrative terpolymers include ethylene / propylene / 1-octene, ethylene / propylene / 1-butene, and ethylene / propylene / diene mono-poly (EPDM).

  In one embodiment, the random polypropylene copolymer is an ethylene graft copolymer made by use of a Ziegler-Natta catalyst, which has an MFR from 1 g / 10 min to 50 g / 10 min at 2.16 kg / 230 ° C. In one embodiment, the random polypropylene has an MFR of 12 g / 10 min at 2.16 kg / 230 ° C. In one embodiment, the random polypropylene has an MFR of 18 g / 10 min at 2.16 kg / 230 ° C.

  In one embodiment, the random polypropylene copolymer has a melting temperature (Tm) that is higher than the Tm of the propylene / alpha-olefin copolymer as determined by differential scanning calorimetry (DSC). One available DSC procedure for determining the melting temperature of random polypropylene copolymers and propylene / alpha-olefin copolymers is that described in US Pat. No. 7,199,203.

(Foaming agent)
Most of any known blowing agents (also known as foaming or swelling agents) can be utilized, including gaseous materials, volatile liquids and chemical agents that decompose into gases and other by-products. Exemplary blowing agents include, but are not limited to, nitrogen, carbon dioxide, air, methyl chloride, ethyl chloride, pentane, isopentane, perfluoromethane, chlorotrifluoromethane, dichlorodifluoromethane, trichlorofluoromethane, perfluoroethane, 1- Chloro-1,1-difluoroethane, chloropentafluoroethane, dichlorotetrafluoroethane, trichlorotrifluoroethane, perfluoropropane, chloroheptafluoropropane, dichlorohexafluoropropane, perfluorobutane, chlorononafluorobutane, perfluorocyclocyclobutane, azodicarboxylic Amide (ADCA), azodiisobutyronitrile, benzenesulfone hydrazine, 4,4-oxybenzenesulfonyl-semicarbazide p- toluenesulfonyl semicarbazide, barium azodicarboxylate, N, N 'dimethyl -N, N'-dinitrosoterephthalamide, and include trihydrazinotriazine. Currently, ADCA is a preferred blowing agent.

(Additive)
The top skin and intermediate foam layer are antioxidants, curing agents, crosslinking aids, foam enhancers and retarders, processing aids, ultraviolet absorbers or stabilizers, antistatic agents, nucleating agents, slip agents Additions including, but not limited to, plasticizers, lubricants, viscosity modifiers, tackifiers, tackifiers, surfactants, extender oils, acid scavengers, and metal deactivators May contain agents. Additives can be used in amounts ranging from 0.01% or less to 10% or more by weight based on the weight of the composition.

(Filler)
Examples of fillers include clays, precipitated silicas and silicates, fumed silica, calcium carbonate, ground minerals, carbon black, and various known flame retardants, especially halogen-free, having an arithmetic average particle size greater than 10 nanometers. Examples include, but are not limited to, flame retardants. Fillers can be used in amounts ranging from zero to 50% by weight or more based on the weight of the layer or total composition.

(Calendar processing process)
The present invention can be manufactured using the same conventional calendering and lamination processes used for PVC-based leather, which is an advantage in terms of capital investment. Propylene-ethylene resins can be readily used in this process because they have little stickiness to the roll surface compared to other ethylene / propylene copolymers. In essence, the glass transition temperature of propylene-ethylene copolymers is relatively higher than that of ethylene alpha-olefin copolymers with high modulus and tack. Furthermore, its melt tension is well suited for lamination, embossing and winding.

  One important factor in calendering is to optimize the roll bank formation conditions, conditions well known to those skilled in the art. This indicates good melt mixing of the resin. Usually, high melt tension requires a high molecular weight resin, but the high molecular weight resin does not melt easily by roll mixing. Good bank formation conditions require a balance between melt tension and fusion.

  The three-layer product includes a backing fabric, a polyolefin foam layer, and a polyolefin top layer, the latter (polyolefin top layer) optionally coated with a primer, and the primer coated with a top coat material. Yes. The top skin layer and the intermediate foam layer are manufactured by a calendering process and then laminated to each other and to the bottom fabric layer in any convenient order. Typically, foaming is performed after lamination, typically in an oven maintained at 220 ° C. or higher for 100-140 seconds. Thereafter, an optional primer and a PU topcoat layer are applied to the top skin layer of the laminate three-layer structure.

[Specific Embodiment]
(Composition and properties of top skin and intermediate foam layer)
Polymers used in these examples include VERSIFY ™, propylene-ethylene copolymer; ENGAGE ™, ethylene / alpha-olefin copolymer; and INFUSE ™, olefin block copolymer (all from The Dow Chemical Company). YUPLENE® R370Y, a random propylene copolymer available from SK Corporation. Rubbers include KRATON ™ MD6945, hydrogenated linear triblock (SEBS) based on styrene and ethylene / butylene available from Kraton Polymer; TUFTEC H1051 rubber and S.R. O. E. ™ SS9000 rubber (both are SEBS rubber and available from Asahi Kasei); and SEPTON ™ 8004 (SEBS rubber), SEPTON ™ 2005 (hydrogenated styrene / ethylene / propylene / styrene block copolymer) and HYBAR ™ 5127 (styrene block copolymer) (all available from Kuraray America). VERSIFY ™ propylene-ethylene copolymer (PER) can be easily processed by calendering and extrusion operations, as well as good feel, flexibility and flexibility without plasticizer, compounding, calendering And a heat-sealable film and sheet that combine compatibility with blends for sheet extrusion. Table 1 further illustrates the polymers and rubbers used in this example.

  Styrenic block copolymers are compatible with polyolefin-based elastomers and provide improved foaming power and improved wettability for solvent-borne CPP primers and PU topcoat materials. The foaming agent is azodicarbonamide (ADCA), which can be used for foam plastics such as PVC, EVA, PP, PE, PS, etc., high-demand and high-density uniform leather and plastic products with uniform pores Used as a foaming agent for manufacturing. This product is a pyrolytic strong organic foaming agent that decomposes at a temperature higher than 120 ° C., for example. Foam promoters include three different types of metallic fatty acids such as zinc stearate, barium stearate and calcium stearate.

  The polymer blend ratio is based on banking conditions and tackiness, and the mechanical properties of the final sheet product. Styrenic block copolymers (SBC) are utilized to obtain the desired foam cell regularity and density, and these also determine the flexibility and properties of the foam layer. The foaming efficiency of the propylene-ethylene copolymer is better without SBC in commercial line conditions than with it. However, SBC is important for the adhesive strength between the uppermost skin layer and the primer and PU topcoat material. Random polypropylene provides heat resistance, toughness and light stability in the top layer.

  Table 2 reports the first series of formulations used to produce the foam layer and the top layer. The unit is percentages (parts per hundred: pph). Table 3 reports the processing conditions and observations for the formulations in Table 1. Tables 4 and 5 report the monitoring results for the second series of formulations and this second series of formulations, and Tables 6 and 7 show the third series of formulations and this third series of formulations. Report on the results of monitoring on the series of formulations.

  Tables 2 and 3 report data on the current product, a conventional artificial leather with a flexible PVC top layer, and an artificial leather within the scope of the present invention. PVC (conventional material most popular in the synthetic and artificial leather market) requires the use of plasticizers that improve molecular chain mobility. However, the products of the present invention do not require the use of plasticizers and not only exhibit flexibility to compete with PVC, but also better mechanical properties, better thermal stability during processing, and better Also provides significant economic benefits (due to its lower density).

  Among the four types of foam layer embodiments, FOAM-1 and FOAM-2 provide better flexibility and feel in terms of foam efficiency, while the FOAM-3 and FOAM-4 embodiments are In view of the Vicat softening temperature, it provides better heat resistance and sufficient flexibility. Comparing the top layer, the example comprising TOP-2 provides better mechanical properties and better thermal stability than the current (PVC) top layer. Examples of FOAM-1 and FOAM-2 show the effect of SEBS on VERSIFY ™ propylene-ethylene copolymer in terms of foaming efficiency (almost no difference), while VERSIFY ™ FOAM-2 using a propylene-ethylene copolymer exhibits better mechanical properties (tensile strength and elongation). Examples of FOAM-3 and FOAM-4 illustrate the effect of RCP on thermal stability and other mechanical properties. The examples of FOAM-1 and FOAM-2 are more suitable for flexible applications such as fashion bags, shoes or garments, regardless of the use of SEBS or VERSIFY ™ propylene-ethylene copolymer, while FOAM-3 And FOAM-4 embodiments are more suitable for industrial applications such as roofing membranes, waterproof fabrics or indoor equipment that require high heat resistance.

  Nicke # 11's Berry Flexibility Test (ASTM D6182) determines the durability of a coating (PU coating material) applied to synthetic leather, leather and cloth by repeatedly bending the specimen. Cracks in the coating can lead to loss of adhesion at the site of use, poor makeup or poor performance. All samples reported in Table 3 demonstrated a berry flexibility in excess of 100,000 cycles at 25 ° C.

  Table 6 reports the photobleaching, cracking and adhesion comparison data for a series of artificial leather samples. Photobleaching is a test method that uses a QUV accelerated weathering tester to determine whether a white or colored sample of a material will turn yellow or fade after exposure of the sample to ultraviolet light, Nike # G37 (AATCC 16 , ASTM G23 / G153) standard. This test includes all fabrics, synthetic leather, leather, yarn, lace, webbing / gore tape, colored components (decorative ink printing or sublimation printing), transparent, clear and translucent rubber, and foam (EVA, Phylon, rubber). ) And plastics (except counters). Cracks are measured according to AATCC 8 (ASTM D5053), a standard test method for the color fastness of leather cracks. This test method addresses the determination of the degree of color that can be transferred from leather to other surfaces by friction under wet (damp) conditions or dry conditions or both. The bond strength (bond or ply strength) is the NIKE # G44 that determines the bond strength between the coated surface and the back layer for all types of materials that are laminated (both wet and dry PU film coating processes). Measured using standards. This includes all synthetic leathers, and sanded or buffed PU coatings on torn leather.

The artificial leather is composed of three layers including a top skin layer, an intermediate foam layer, and a bottom backing layer. The backing fabric is a base substrate for maintaining the shape and mechanical properties of the artificial leather, and easily affects the tactile sensation (hand) of the leather. Therefore, in terms of mechanical properties and tactile sensation, the choice of lining is also important for obtaining suitable leather properties. In these examples, the backing is a high weight spunbond (310 g / m ² , thickness 1.2 mm, width 58 inches) fabric.

  Adhesive strength and belly flexibility are primarily used in shoe manufacturing and are excluded for other leather applications such as clothing, bags, interior decoration, waterproof fabrics and the like. There are five different types of leather systems based on the material used for the top layer or foam layer. A system comprising SEBS exhibits sufficient properties that are acceptable for shoe manufacture in terms of adhesive strength and belly flexibility. Except for adhesive strength and belly flex, most of the properties are satisfactory compared to current specifications and all systems can be applied to other leather applications (except shoes). Calendering and lamination with finishing processes such as priming and PU topcoat coating are suitable for commercial applications.

  Based on the Nike # 44 standard measurement method, the adhesive strength between the coated surface (PU top coat on the top layer) and the back layer (bottom rubber bottom of the shoe) should be at least 2.5 kgf / cm after 24 hours. . Table 7 describes the performance of the various top layer formulations for adhesive strength. After the top layer is treated with a solvent-type chlorinated polypropylene (CPP) primer and a PU topcoat material, an adhesive strength test is performed. Songstab SZ-210 is a zinc stearate activator available from Songwon Chemical. AC1000 is an azodicarbonamide blowing agent available from Kumyang Chemical.

  The adhesive strength between the uppermost skin layer and the PU topcoat layer is improved by using a primer. Styrenic triblock or diblock copolymers with good compatibility with polypropylene act as an effective bridge between the propylene-ethylene copolymer and the PU coating. Given the polarity of a primer that is CPP, styrenic triblock or diblock copolymers impart polarity to nonpolar polyolefin materials such as propylene-ethylene copolymers, increasing the bond strength between the primer layer and the top layer. Therefore, the addition of SEBS-1 with good compatibility and polarity with PP showed acceptable bond strength between the top layer and the PU topcoat material in combination with the primer.

The foam ratio is based on the flexibility and softness of the foam layer and also on the mechanical properties targeted for a tear strength of 15 kgf / cm ² and a heat resistance of 130 ° C. or less. Experimentally, it has been found that a foaming rate of 50-350%, preferably 200-250%, is most suitable for artificial leather. If the foaming efficiency is higher than 250%, most of the foamed cells are united and the foam is likely to dent. Pre-foaming during calendering is avoided because the foaming agent is already mixed with other resins during calendering. By waiting for the foaming process, foam layers with good cell regularity and cell structure are made, which ultimately affect the flexibility and feel of the artificial leather. The roll bank forming conditions are the same as the production of the uppermost layer under the same calendering temperature conditions. Propylene-ethylene copolymers having a lower density than that of PVC or PU or SBC are a better choice because the foam layer makes the leather lighter in addition to providing flexibility.

  The VERSIFY ™ 2000 series demonstrated a calendaring winding performance comparable to PVC and TPU, which are current materials for synthetic leather production.

Among the formulations that use blends of OBC or POE and PER-4, D3 and D6 have better calendering performance than others, with the exception of foaming efficiency, D6 is foaming efficiency and mechanical properties Shows the best balance. The calendering performance is based on bank formation conditions and winding efficiency and is determined by MFR from 2 to 4 g / 10 min at 230 ° C. and density from 0.86 to 0.88 g / cm ³ .

  Foaming of the sheet layer is performed at 220 ° C. for 100 to 120 seconds in an oven after calendering. Prevention of premature foaming is important to achieve a fine and regular cell density. The AC100, which is ADCA used for foaming leather seats, is controlled to improve foaming efficiency. When the calendaring run temperature is in the range of 150 to 160 ° C., the optimum concentration of blowing agent is about 4 pph. In the case of PER-4, blowing agent concentrations higher than 6 pph can cause premature foaming despite other performance factors such as winding in calendering being fully achieved.

  It is known that the addition of fillers to the foam sheet formulation hinders the propagation of foam within the molecular chain, so fillers are usually not recommended for use during foaming. However, the filler can be used to improve the mechanical properties of the foam sheet.

Claims (10)

A.
A propylene / ethylene copolymer;
An ethylene / α-olefin multiblock copolymer represented by the formula: (AB) n, wherein n is at least 1, A is a hard block, B is a soft block, and the hard block is Having greater than 95 weight percent ethylene and less than 5 weight percent α-olefin comonomer (wt% based on the total weight of the hard block), the soft block being greater than 5 weight percent α-olefin An ethylene / α-olefin multiblock copolymer having comonomer and the balance ethylene (wt% based on the total weight of the soft block);
Optionally, an uppermost skin layer A comprising (i) at least one of a styrenic block copolymer, (ii) a homogeneously branched ethylene / α -olefin copolymer, and (iii) a random polypropylene copolymer;
B.
A propylene / ethylene copolymer;
An intermediate foam layer B comprising: (i) a styrenic block copolymer; (ii) a uniformly branched ethylene / α -olefin copolymer; (iii) an olefin block copolymer; and (iv) a random polypropylene copolymer;
C.
A bottom fabric layer C comprising a non-woven, polymeric spunbond material;
Including multi-layer structure.   The multilayer structure according to claim 1, further comprising a primer layer in contact with the uppermost skin layer and a topcoat layer in contact with the primer layer. The multilayer structure according to claim 1 or 2, wherein the propylene / ethylene copolymer has a substantially isotactic propylene sequence. 4. A multilayer structure according to any of claims 1 to 3, wherein the styrenic block copolymer comprises at least two mono-alkenyl arene blocks separated by a block of saturated conjugated diene containing less than 20% residual ethylenic unsaturation. The homogeneously branched ethylene / α -olefin copolymer is produced using a single site catalyst and has a melting point of less than 95 ° C. and an α-olefin content of at least 15 weight percent based on the weight of the copolymer. A multilayer structure according to any one of claims 1 to 4. The intermediate foam layer comprises the olefin block copolymer , wherein the olefin block copolymer has the formula: (AB) _n , wherein n is at least 1, A is a hard block, and B is a soft block; And A and B are linearly linked)), an ethylene / α-olefin multiblock copolymer
The hard block has greater than 95 weight percent ethylene and less than 5 weight percent α-olefin comonomer (wt% based on the total weight of the hard block);
The soft block has an amount of α-olefin comonomer greater than 5 weight percent and the remainder ethylene (wt% based on the total weight of the soft block);
The multilayer structure according to any one of claims 1 to 5.   7. The random polypropylene copolymer according to any one of claims 1 to 6, wherein the random polypropylene copolymer comprises 90 mole percent or more units derived from propylene, the balance being units derived from at least one α-olefin unit. Multi-layer structure.   The multilayer structure according to any one of claims 1 to 7, wherein the bottom layer fabric is prepared from at least one of polyester, polyethylene and polypropylene. At least one of the uppermost skin layer and the intermediate foam layer is an antioxidant, a curing agent, a crosslinking aid, a foaming accelerator and a retarding agent, a processing aid, a filler, an ultraviolet absorber or a stabilizer, an antistatic agent, It further comprises at least one of a nucleating agent, slip agent, plasticizer, lubricant, viscosity modifier, tackifier, anti-tack agent, surfactant, extender oil, acid scavenger, and metal deactivator. A multilayer structure according to any one of claims 1 to 8. The multilayer structure according to any one of claims 1 to 9, wherein the uppermost skin layer , the intermediate foam layer, and the bottom fabric layer are joined to each other by thermal lamination.